Circuit breaker



Dec. 2, 1941. DQRF'MAN 2,265,030

CIRCUIT BREAKER Filed March 25, 1958 4 Sheets-Sheet l WITNESSES: INVENTOR 9%? MM /7/// er Q Dar/$77477.

. 2, 1941. H. D. DORFMAN CIRCUIT BREAKER Filed March 25, 1938 4 Sheets-Sheet 2 mm m.

INVENTOR /////er 0 flar/zmrz WITNESSES: 9% yzg w Patented Dec. 2, 1941 CIRCUIT BREAKER Hiller D. Doriman, Forest Westinghouse Electric pany, East Pittsburgh,

Pennsylvania liflinra assignorto & Manufacturing Oom- Pa., a corporation of Application March 25, 1938, Serial No. 198,076

14 Claims.

The invention relates to circuit breakers, in general, and more particularly to circuit breakers of the type in which the breaker operating means is manually operable to open and close the circuit, and is automatically operable to open the circuit in response to overload or short cir cuit conditions.

An object of the invention is the provision of a circuit breaker embodying an improved trip mechanism that is operable to eiiect opening of the breaker after a predetermined time interval in response to lower magnitude overloads in the controlled circuit, and operable to effect opening of the breaker immediately upon the occurrence of higher magnitude overloads or short circuit conditions in the controlled circuit.

Another object of the invention is the provision of a circuit breaker with an improved trip device embodying a thermally responsive trip element and an electromagnetic trip means, in which at least a portion of the energizing winding of the electromagnetic trip means serves as the heater for the thermally responsive trip element.

Another object of the invention is the provision of a circuitbreaker with an improved electromagnetic trip means, the magnetic frame and armature of which are constructed of sheet metal and formed to the desired shape.

Another object of the invention is the provision of a circuit breaker with an enclosed trip device embodying a thermal trip element the trip characteristic of which is set during the assembly and calibration of the device, and an electromagnetic trip means the trip characteristic of which is adjustable within predetermined limits from outside the enclosure.

Another object of the invention is the provision of a circuit breaker trip device having an electromagnetic trip means, with an improved adjusting means for adjusting the trip characteristic of the trip means; the adjusting means including a movable member that is permanently set during the assembly and calibration of the breaker to provide a selected range of adjustment, and an operating member that is movable at will to adjust the trip characteristic within the pre-selected range.

Another object of the invention is the provision of an enclosed circuit breaker with a trip device mounted within the enclosure and an adjusting means that is operable from. outside the circuit breaker enclosure to vary the trip characteristic of the trip device.

Another object of the invention is the provision of a circuit breaker embodying an improved trip device, as described above, that is simple, reliable in operation, and inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation together with additional objects and advantages thereof will best be understood from the following detailed description of a preferred embodiment thereof when read in connection with the accompanying drawings in which,

Figure 1 is a plan view of a circuit breaker provided with the trip device of the present invention; a portion of the breaker enclosure cover having been cut away and the cover of the trip device removed to show certain structureal features of the breaker and trip device.

Fig. 2 is a vertical sectional view of the circuit breaker shown in Fig. 1.

Fig. 3 is an enlarged plan view of the trip device, a portion of the cover being cut away to show certain structural details of the device.

Fig. 4 is a vertical sectional view of the trip device taken substantially on the line IV-IV of Fi 3.

Fig. 5 is a fragmentary end elevational view of the circuit breaker illustrating the operating member of one of the adjusting means of the trip device.

Fig. 6 is an enlarged plan view of the magnet frame and armature of one of the electromagnetic trip means of the trip device.

Fig. 7 is a view of the electromagnetic trip means shown in Fig. 6 and taken at right angles thereto.

Fig. 8 is a front elevational view of the adjusting means for one of the electromagnetic trip means.

Fig. 9 is a side elevational view of the adjusting means shown in Fig. 8. 1 Fig. 10 is a view of the magnetic stamping before being formed into the magnet frame, and

Fig. 11 is a fragmentary sectional view or a portion of the trip device showing the manner in which the electromagnetic trip means is secured to the base of the trip device.

Referring to the drawings. and particularly Figs. 1 and 2 thereof, the circuit breaker illustrated is of the three-pole type and comprises in general a base I, of a molded insulating material having a cover 3 also of molded insulating material, removably mountedthereon, a plurality of stationary contacts I and a plurality of movable switch members 1 carrying movable contacts 9 which cooperate with the stationary contacts I to form the poles of the breaker, a common operating mechanism indicated generally at H for the switch members, and a imitary trip device indicated generally at l9.

The base I has a plurality of end terminals l9 and I1 mounted thereon adjacent each end by means of terminal screws |9 which engage threaded terminal inserts 2| imbedded in the base. The poles of the breaker are insulated from each other by insulating barriers 22 formed integral with the base I, which align with similar barriers 29 formed integral with the cover 9.

Each stationary contact member I (onlyone being shown) is mounted on the inner end of a strip 25 of conducting material which is secured to the base by means of a screw 21 and connected at its other end to the corresponding end terminal I! by the terminal screw l9.

Each movable switch member 1 comprises a channel-shaped steel frame to the outer end of which is pivoted a contact carrying arm 29. The arm 29 has a stop 9| which engages the frame of the switch member 1 to limit counter-clockwise rotation of the arm 29 relative to the switch member 1. The-movable contact 9 is secured to the outer end of the contact arm 29 for movement into and out of engagement with the co operating stationary contact 9. The contact carrying arm 29 is provided with a tail piece 99 which is adapted to engage a spring pressed plunger 99 carried by the base I, when the switch member is in closed circuit position. The spring pressed plunger 99 serves to provide a definite contact pressure between the movable contact 9 and the stationary contact 9 when the breaker is in closed circuit position.

All three of the switch members 1 have square openings provided therein adjacent their rear ends. An insulating tie bar 91 which extends across all three poles of the breaker engages the three square openings in the switch members 1 to mechanically connect the switch members for simultaneous movement by the common operating mechanism l I. The center pole switch member 1 is pivotally mounted on a U-shaped frame 39 by means of a pivot pin 9| which extends transversely between the side walls of the frame 99. The pin 4| serves to provide a common pivot axis for the assembly of switch members 1, all of which are mechanically tied together by the in-- sulating tie bar 91.

The movable contacts 9 carried by the switch member 1 are electrically connected by means of flexible shunt conductors 49 to a plurality of U-shaped terminal members 99 (Fig. I) mounted on the base by means of terminal screws 41 which engage threaded inserts 99 (Fig. 2) imbedded in the base The terminal members 95 are adapted to be removably electrically connected to the corresponding terminals of the trip device l9 by means of the terminal screws 91.

The electrical circuits for each of the poles of the breaker are "substantially the same. Beginning with the terminal IS, the current passes successively through the conducting strip 29, stationary contact 5, movable contact 9, and its associated conducting shunts 99, through the unitary trip device l9, and thence to the other end terminal l1.

spaced plate type in which a plurality of slotted magnetic plates 92, each insulated from the other, is provided. Each arc extinguishing means 9| is disposed adjacent the arc path of its corresponding pair oi contacts and is operable upon the establishment of an arc to move the are into the spaces between the plates 92 where .it is immediately cooled and extinguished in a well known manner.

The cover 9 of the circuit breaker is provided with a plurality of screened openings 59 which form an exit for the escape of hot gases which may be formed during circuit interruption. The cover 9 is also provided with a baille for directing the arc gases through the screened openings 53 and for preventing these gases from escaping through the opening provided in the cover for the operating handle.

The operating mechanism ll of the circuit breaker is carried by the U-shaped frame 99 which is secured to the base by means of a plurality of screws 91. The mechanism comprises in general, the U-shaped operating member 59 pivoted on the sides of the frame 99 by means of pivot pins 99, a releasable cradle 9| which is pivoted on the frame 99 by means of a pivot pin 99, a pair of toggle links 95 and 91 and a pair of over-center springs 99 (only one being shown). The toggle link 91 is pivotally connected at its lower end by means of a pivot pin 1| to the central switch member 1 and has its upper end pivotally connected to the lower end of the toggle link 99 by knee pivot pin 13. The upper end of the toggle link 95 is pivotally connected to releasable carrier 9| by means of a pivot pin 15. The overcenter springs 99 have their upper ends connected to the bight portion of the U-shaped operating member 99 and their lower ends pivotally connected to the knee pivot pin 13 which connects the links 99 and 91. The operating member 59 has an operating handle 11 of molded insulating material secured to the upper end thereof. The handle 11 has an operating knob 19 which extends through an elongated opening 9| provided therefor in the cover 9, and with an arcuate shield portion 99 which serves to close the opening 9| in all positions of the operating member.

The carrier 9| is always biased in a clockwise direction about its pivot pin 93 by a component of the force exerted by the over-center springs 99. The free end oi! the carrier 6| has a latch An arc extinguishing means indicated at 9| is provided for each pair of the contacts of the breaker. The are extinguishing means 5| may be of any suitable type, but is preferably of the nose 95 which is normally engaged by a latch of the trip device l9 to hold the carrier 9| in a normal position, as shown in Fig. 2.

The trip device I9 is a unitary structure entirely assembled on its own base 91 which is of molded insulating material. A cover 99 of insulating material is mounted on the base 91 and cooperates therewith to form an enclosure for the trip mechanism assembled on the base 91. The trip device is removably mounted on the base I of the circuit breaker, in a suitable recess provided therefor adjacent one end of the base I, by means of a pair of elongated screws 9| (Fig. 3) which pass through the cover 99 and base 91 and engage in threaded inserts (not shown) embedded in the base l of the circuit breaker. The trip structure l9 includes a thermally responsive trip element 99 and an electromagnetic trip means indicated generally at 99 for each of the three poles of the breaker.

Each of the thermally responsive trip elements 99 is composed of suitable bimetallic material and has its lower end riveted to the angularly bent end of a conducting strip 91, so as to be disposed members 45 of the circuit breaker.

in a vertical position. Each strip 91 is secured to the under side of the forward end of the base 91 by a transverse terminal plate 99 which is rigidly clamped to the base 91 by a pair of rivets I9I (Fig. 4). The forward end' of the base 91 has three spaced recesses I99 (Fig. 3) which extend through the base to the terminal plates 99 for accommodating the intermediate terminal The three terminal plates 99 have openings for receiving the intermediate terminal screws 41 of the breaker which serve to clamp and electrically connect the terminal members 45 to the terminal plates 99 of the trip device.

The opposite terminals I95 of the trip device comprise three conducting strips which are secured to the base 91 by means of screws I91 which extend upwardly through openings in the bottom of the base 91 and engage the strips I95 to clamp them to the base 91. The strips I95 have oil'set portions I99 which are perforated to receive the end terminal screws I9 of the circuit breaker which serve to clamp and electrically connect the terminals I95 of the trip device to the end terminals I1 of the circuit breaker.

Each of the three magnetic trip devices 95 comprises a U-shaped frame III which is cut from a plate of magnetic material and formed into the shape shown in Fig. 10. The plate is formed to a-U shape by bending the leg portions H9 at right angles to the bight portion I I5 and then the flaps II1 of the legs II9 are bent at right angles inwardly along the dotted lines II9 (Fig. to provide parallel inwardly directed flanges I29 (Figs. 6 and 7). A U-shaped magnet I2I formed from a strip of magnetic material is nested within the U-shaped frame I and secured thereto by a center core member I29 which has a reduced portion I25 which extends through openings provided therefor in the bight portions of the frame III and magnet I2I. the reduced portion I25 of the core member I29 is spun over against the back of the U-shaped frame I I I and thus serves to clamp the U shaped magnet I2I to the frame III and to retain the core member I29 in mounted position. One of the legs 9 of the magnet frame II I has a pair of projecting ears I25 which are provided with aligned openings for receiving a pivot pin I21 for pivotally mounting an armature I29 to a leg of the magnet frame II I. The armature I29 consists of two strips I9I of magnetic material secured together face to face, and the strips I9I have opposed bump shaped bends I99 formed therein adjacent one end of the armature to provide a transverse opening for receiving the pivot pin I21. The armature I29 is thus pivotally mounted on one leg II9 of the magnet frame III for swinging movement into engagement with the end of the other leg II9 of the frame by means of the pin I21 which extends through the aligned openings of the ears I25 and through the transverse opening of the armature I29. The armature is biased away from the core I29 by means of a coil spring I95, the ends of which seat in wells I91 and I99 provided therefor in the core member I29 and armature I29 respectively.

The three assembled magnetic trip means 95 are mounted in spaced relation on the base 91 in recesses provided therefor, and each electromagnetic trip means is clamped in mounted position on the base 91 by means of a plurality of rivets I which pass through openings provided in the inturned flanges I29 of the legs I I9 of magnet frame III as shown in Fig.11.

The end of Each of the electromagnetic trip means is provided with an energizing winding I49 which consists of a curved copper strip I45 riveted to the angularly bent inner end of the conducting strip I95 and which encircles the core I29 of the electromagnetic trip means 95, and a second curved strip I41 composed of a suitable high electrical resistance material such asnickel or nickel alloy. The strip I41 is riveted at one end to the end of the copper strip I45 and also encircles the core member I29. The opposite end of the strip I41 is secured to the conducting strip 91 by means of the rivet which connects the bimetal trip element 99 to the strip 91. The two strips I45 and I41 are of such shape that they form a substantially helical winding encircling the core member I29, which is connected in series circuit with a corresponding pair of the contacts of the breaker. The high resistance strip I41 has a portion disposed in contact with a portion of the corresponding bimetal. trip element 99 so that the strip I41 in addition to forming part of the energizing winding for the electromagnetic trip means 95 also serves as the heater for the bimetal trip element 99.

A common trip bar I49 of molded insulating material extends transversely across the three poles of the trip .device I3 and is actuable by any one of the three bimetallic trip elements 99, and also by any one of the three electromagnetic trip means 95. The trip bar is pivotally mountled on a pair of brackets I5I (Fig. 3) and is biased in a clockwise direction by means of a coil spring I59 which is connected between the trip bar and a, bracket on the base 91. The trip bar I49 has three spaced downwardly extending projections I55, the lower ends of which are disposed in the path of movement of the armature I29, so as to be engaged and moved by the armatures when the armatures are moved to attracted position. The trip bar I49 is also provided with three spaced upwardly extending projections I 51 which carry adjusting screws I59 at their upper offset ends adapted to be engaged by the upper free ends of the bimetallic trip elements 99. It will thus be seen that the trip bar I49 is adapted to be partially rotated in a counter-clockwise direction from its normal position shown in Fig. 4 to a tripping position by any one of the three bimetallic trip elements 99 in response to moderate and.lower magnitude overloads of predetermined duration, and the trip bar is also par- V tiaily rotatable in a counter-clockwise direction from its normal position to its tripping position by any one of the electromagnetic trip means 95 in response to heavy overloads and short circuit conditions.

The trip device is provided with a latch member I5I which normally engages and restrains the carrier 5| to maintain the toggle links in operative position for operation by the operating member of the breaker. The latch member I9I is slidably pivoted on a pivot pin I69 which is carried transversely betweenthe legs I65 01' a yoke-shaped bracket I91. The bracket I51 is secured to the base by means of the rivets I III which retain the central pole terminal plate 99 to the trip base 91. The latch member I5I has a rearwardly extending notched projection I59 which is normally engaged by a projection I1I secured to the trip bar I49. The latch member I9I has two slots I19 for slidably engaging the pivot pin I69. A spring I15 which is coiled about the pivot pin I59 exerts a force which biases the latch member I9I in a clockwise direction about ihepivotpin itlandaisobiasesthclatchmemher in the direction oi the operating II as far as permitted by the slots I13. The movement of the latch member "I in a clockwisedirectionundertheinnuence oithe spring Iii is limited by the engagement of the yoke portion oi the latch member III with the yoke portionoi'thebracket Illasbestshowninl'ig.4. when the releasable carrier I or the circuit breaker is restrained in its normal position, that is, when the latch nose It thereof is engaged under the latch projection Ill or the latch member it], the latch member is biased in counterclockwise direction due to the relatively large force transmitted thereto by the carrier I. This force is balanced by the trip bar I which. through its projecting portion III, releasably engages the notched end oi! the projection III of the latch member III and prevents the latch member from turning under the biasing action oi'the carrier II. when the trip bar Ill ismoved in a counter-clockwise direction to its tripped position, it eilects release of the latch member itl which in turn releases the carrier II of the circuit breaker to eiiect a trippin operation as will be hereinafter described.

The yoke shaped bracket I" has a pair of projecting legs I" provided with notches Ill which engage projections I12 extending from the side walls of the frame I! so as to accurately position the trip device I3 with respect to the breaker mechanism II.

Each of the three electromagnetic trip means 85 is provided with an individual adjusting means indicated generally at I10 which serves to adjust the trip characteristic oi! the trip means. Each of the adjusting means I'll (Figs. 8 and 9) includes an angular bracket Iii which has its horisontal leg clamped against the base ll of the trip device by means or the rivets Ill which secure the magnet assembly oi the electromagnetic tripping means "to thebasell. asshowninl 'ig. 11. The bracket III is insulated from the conducting strip II! by means of an insulating plate I83. The vertical leg III of the bracket IlI extends across an opening provided therefor in the end the base I! of the trip device, and is provided with an arcuate slot Ill and with a keyhole Ill. A warped spring washer "I is disposed against the inner surface of the leg Ill of the bracket III, and this washer is provided with a keyhole slot 102 which cooperates with the keyhole slot Ill in the vertical leg I" of the bracket III to mount a calibrating screw Ill. Thescrew iaihasareducedportion Iflandathreaded portion Ill. The screw I is mounted by placing the washer III against the leg I of the bracket III with the keyhole slots "2 and I in,thescrewIllbeinginserted through the enlarged portions of the keyhole slots and the reduced portion of the screw slipped into the reduced portion of the slots. The spring washer Iii is then rotated 180', as shown in Fig. 8. to retainthe calibrating screw I" inmounted position. The enlarged threaded portion I" and thcheadoithescrewservetoretainthesprlng washer in tension with its edges against the verticalieg Ill'oi the bracket Itl.

I An angle shaped operating lever I" has a threaded hub portion 2" which is threadedly mounted on the threaded portion In of the callbrating screw I" (Fig. 9). The operating lever I has an oiiset portion 2|! which extends through an opening provided therefor in the assume in! Ill 0! thebracket III. The lever I is also provided with an angular projection III which is normally engaged by the armature I2! oi the electromagnetic tripping means I, as shown in Fig. 4. The rotatable adjusting movementoi' the lever I" is limited by the arcuate slot Ill oi the bracket Itl.

During the-assembly and calibration of the breaker, each oi the electromagnetic trip means I is given a preliminary setting or calibration by turning the calibrating screw I93 to obtain the correct maximum trip current setting or the correct range of adjustment of the electromagnetic trip means lI. when the electromagnetic trip means has been correctly calibrated by means of the adjusting screw I, the operating lever III is soldered to the threads of the callbrating screw I" to make the preliminary adjustment permanent. Alter the three electromagnetic tripping means 95 have been calibrated, as described above, the trip characteristic of each can be varied over a selected range by rotating the operating lever Ila.

The rotation of the operating lever in a counter-clockwise direction, asviewed in Fig. 4, serves to increase the air gap between the armature I2! and the core I23, so that a larger amount 0! current is required to cause movement of the armature I2! to attracted position to eilect the tripping operation of the device. Conversely rotation of the operating lever I98 in a clockwise direction serves to move the armature I29 closer to the core I23, reducing the air gap so that the electromagnetic trip means 95 will be operated in response to a lower current value. Thus the trip characteristic of each of the electromagnetic means 88 may be individually adjusted through a selected range by means of the adjusting means I". The spring washer m oi each of the adjusting means I18 is provided with a projection 2" (Figs. 8 and 9) which engages arcuately arranged serrations 209 provided in the leg I" of the bracket Isl. The projections 201 and the serrations 2 provide a notching means for releasably retaining the operating lever I" in any adjusted position to which it is spring disk Iii and through the arcuate openset. Each of the three adjusting means I" is provided with a shield 2 (Big. 4) of insulating material which has a recess through which the offset operating projection 20! oi. the operating lever I89 projects. The vertical leg I of the bracket III is provided with a suitable calibration scale 2|! and with indicia 2|! for indicating the high and low adjustment of the operating lever I", and the scale and indicia are visible from outside the enclosure of the trip device through the recess in the shield III as shown in Fig. 5. It will be noted from Figs. 2 and 5 of the drawings that the shields 2i I cover the heads of the calibrating screws I so as to prevent access thereto from outside the circuit breaker enclosing casing I-3. An additional deterrent to unauthorized change in the setting of the calibrating screws is provided by the fact that the operating levers III are soldered or otherwise sealed to the calibrating screws'aiter calibration of the device, as described above.

The base I of the circuit breaker is provided with three rectangular openings 2II (Fig. 5) in the end wall thereof adjacent the trip device II. The openings 2" permit access to be had to each of the adjusting means I.

The trip characteristic of each of the bimetallic trip elements I! is adjustable by,means oi the adjusting screw I" and the trip characteristic of each of the bimetallic trip elements 05 is set during the assembly and calibration oi the breaker, and the setting thus given is preferably made permanent by soldering the lock nut III which is mounted on the adjusting screw I59.

The operation of the circuit breaker is briefly as iollows: With'the breaker in open position, as shown in Fig. 2, let it be assumed that it is desired to manually close the circuit breaker. The operating member 58 is moved by means a handle I! in a clockwise direction about its pivot axis from the open circuit position shown in Fig. 2 to the'closed circuit position. This movement of the operating member 58 moves the line of action oi the over-center springs 88 to the right. As soon as the line of action 01' the over-center springs it crosses the pivot pin I5 which connects the upper gle link 65 to the carrier GI, the force exerted by the springs moves the toggle links from their collapsed position, as shown in Fig. 2, to a made or in toggle position, causing the three mechanically connected movable switch members I to move to closed circuit position with a snap action carrying the movable contacts 5 into engagement with the stationary contacts 5. To open the circuit breaker, the operating member 58 is moved in a counter-clockwise direction about its pivot axis 59 from the closed position to the open position shown in Fig. 2. This movement of the operating member 58 moves the line of action of the over-center springs to the left. As soon as the line of action of the over-center springs crosses the axis of the pivot pin 15, the force exerted by the springs moves the toggle links 65 and 51 to their collapsed position, causing movement 01' the mechanically connected switch member I to open circuit position with a snap action and carrying the movable contacts 5 to open circuit position, as shown in Fig. 2.

When the breaker is in closed circuit position and an overload occurs in the circuit through any one of the poles of the breaker, the heater portion of the energizing winding I of the afl'ected pole is heated, and since the bimetallic element 93 is in intimate contact with the heater portion 01 the winding, this element is also heated. When the bimetallic trip element 83 has been heated a predetermined amount, it deflects in a direction away from the operating mechanism II and eilects movement oi the trip bar I49 to tripping position. Movement of the trip bar I49 to tripping position efiects release of the latch member IOI which, in turn, releases the carrier SI of the breaker operating mechanism. When the carrier II is released, it is rotated in a clockwise direction about its pivot pin 63 and causes collapse of the toggle links 55 and 61, thereby opening the contacts of the breaker. Similarly, in'the event of a short circuit or a heavy load in a circuit controlled by any one 01 the poles, suilicient magnetomotive force is supplied by the energizing winding I 43 oi the aiiected pole to cause the corresponding armature I29 to be attracted to the core member I23. The movement oi the armature I29 to attracted position causes movement of the trip I49 to its tripped position to effect release of the carrier 6| and opening of the breaker as previously described in connection with the thermal trip operation.

Before the circuit can be reclosed following a tripping operation, it is necessary to reset the operating mechanism. A projection I on the operating member 58 is provided for this purpose. To reset the mechanism, the operating handle 1'! is moved in a counterclockwise direction, during which movement, the projection 22I engages and moves the carrier GI in a counterclockwise direction. As the operating handle I1 nears the limit or travel in an opening direction, the latch nose of the carrier 6| engages the over-hanging projection I" of the latch IBI, and slides the latch member IBI in a rearward direction to allow the latch nose 85 to clear the projection I". When the handle 11 is released, the carrier GI is returned a short distance by the overcenter springs 69 to its normal latched position where it is held by the latch member 'IGI, the latch member I6I, having been returned to its latched position by the spring I15 and reengaged by the projection I 'II on the trip bar I49. The entire breaker mechanism is now in open and reset position and may be closed by movement 01 the operating handle TI to closed position as has previously been described.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from the spirit of the "invention. It is desired, therefore, that the appended claims be given the broadest reasonable clliistruction permissible in the light of the prior a I claim as my invention:

1. In a circuit breaker having relatively movable contacts, a trip device operable in response to predetermined conditions to cause opening of said contacts comprising a core member, a movable armature, an energizing winding encircling said core comprising a flat strip of conducting material making more than one turn about said core and disposed with its flat sides perpendicular to the axis of said core, and a thermally responsive trip element disposed in heat transferring relation to said winding between turns thereof to be heated thereby.

2. In a circuit breaker having relatively movable contacts and an actuating mechanism therefor, a trip device operable in response to predetermined conditions to eiiect opening of said contacts comprising a core member; a movable armature, a substantially helical energizing winding for said core member connected in circuit with said contacts comprising a flat strip of conducting material making at least one complete turn about said core and disposed withits flat sides perpendicular to the axis of said core, said winding strip having a portion of increased electrical resistance, and a thermally responsive trip element having a portion thermally conductively joined to the increased resistance portion of said winding strip to be heated thereby.

3. In a circuit breaker having relatively movable contacts and an actuating mechanism therefor, a trip device operable in response to predetermined conditions to effect opening of said contacts comprising a core member, an armature for said core member movable to an attracted position to efiect operation of the trip device, an energizing winding for said core connected in circuit with said contacts comprising a flat strip of conducting material making at least one complete tum about said core and disposed with its flat sides perpendicular to the axis oi said core, said winding having a portion of increased electrical resistance, and a bimetallic trip element having a portion thermally conductively joined to the increased resistance portion of said winding strip to be heated thereby, said element being operable when heated a predetermined amount.

4. In a trip device for a circuit breaker, a core member, a movable armature for said core member, a multi-tum energizing winding encircling said core comprising a flat strip of conducting material making at least one complete turn about said core and wound with its flat sides perpendicular to the axis of said core, said windinghaving a portion of increased electrical resistance; and a thermally responsive trip element having a portion thermally conductively Joined to the increased resistance portion of said winding to be heated thereby.

' 5. In a trip device for a circuit breaker, a core of magnetic material, a movable armature for said core, a pair of terminals for connecting said device in the circuit, an energizing winding for said core comprising a flat strip of conducting material making more than one turn about said core and wound with its flat sides perpendicular to the axis of said core, said winding being supported by and connected between said terminals, and a bimetallic trip element supported by one of said terminals and having a portion thermally conductively joined to a portion of said winding between turns thereof so as to be heated by said winding.

6. In a trip device for a circuit breaker, an electromagnetic trip means comprising a generally U shaped member having legs which are provided with integral flange portions projecting inwardly from the edges of said legs, said memher being cut and formed from a plate of magnetic material, an armature pivotally mounted on one of the legs of said member adjacent the end thereof for swinging movement into engagement with the other leg, and an energizingwinding for said member.

7. In a trip device for a circuit breaker, an electromagnetic trip means comprising a member cut from a strip of magnetic material and formed to provide a U shaped frame, one of the formed therein adjacent their one end to provide a transverse opening for receiving a pivot pin, said armature being pivotallymounted on said one leg for swinging movement into engage ment with the other leg by a pivot pin which extends through aligned openings provided therefor in said ears and through the transverse opening of said armature.

8. In a trip device for a circuit breaker, an electromagnetic trip means comprising a member cut from a plate of magnetic material and formed to provide a U shaped frame, the legs of which are U shaped in section, a U shaped magnet secured to said frame and nested within the same, a core of magnetic material mounted on the bight portion of said magnet intermediate the legs thereof, an armature pivotally mounted on one of the legs of said U shaped frame for swinging movement into engagement with the end of the other leg, and an energizing winding encircling said core.

9. In a circuit breaker having relatively movable contacts, a trip device operable to effect opening of said contacts in response to predetermined conditions comprising an electromagnetic trip means including a core and a movable armature biased away from said core and movable to an attracted position to effect operation of said trip device, spring means for biasing said armature away from said core, adjusting means for varying the trip characteristic of said electromagnetic trip means comprising an operating member mounted for limited rotatable adjusting movement to vary the normal position of said armature, and movable means for shitting the position of the rotatable operating member relative to the core to select the range of adjustment of said adjustable means.

10. In a circuit breaker, an enclosing casing, relatively movable contacts in said casing, a trip device in said casing operable to effect opening of said contacts in response to predetermined conditions comprising an electromagnetic trip means including a core and a movable armature biased away from said core and movable to an attracted position to eii'ect operation of said trip device, adjusting means for varying the trip characteristic of said electromagnetic trip means comprising a movable operating member normally engaged by said armature, and mounted for limited adjusting movement for varying the normal position of said armature, said operating member being accessible from outside said casing, and means movable to shift the movable operating member toward or away from said core to calibrate the device for the maximum current setting, said last-mentioned movable means being substantially inaccessible from outside said casing.

1l. In a circuit breaker, an enclosing casing, relatively movable contacts in said casing, a trip device in said casing operable to effect opening of said contacts in response to predetermined conditions comprising an electromagnetic trip means including a core and a movable armature biased away from said core and movable to an attracted position to eflect operation of said trip device, adjusting means for varying the trip characteristic of said electromagnetic trip means comprising a movable operating member normally engaged by said armature, and mounted for limited adjusting movement for varying the normal position of said armature, said operating member being accessible from outside said casing, and means movable to shift the movable operating member toward or away from said core to calibrate the device for the correct maximum current setting, and notching means for releasably retaining said operating member in any adiusted position to which it is moved, said movable calibrating means being inaccessible from outside said casing.

12. In a circuit breaker, an enclosing casing,

relatively movable contacts in said casing, a trip device mounted in a second enclosing casing inside the breaker enclosing casing, said trip device being operable to effect opening of said contacts in response to predetermined conditions and comprising an electromagnetic trip means including a core and a movable armature biased away from said core and movable to an attracted pomtion to effect operation of the trip device and a thermally responsive bimetal element heated in response to the current of the circuit and operable when heated a predetermined amount to eifect operation of the trip device, said bimetal element being given a permanent setting during the assembly and calibration of the device; and adjusting means for adjusting the trip characteristic of said electromagnetic trip means comprising a movable operating epsaoso member normally engaged by said armature and mounted for limited adjusting movement to adjust the normal position of said armature relative to the core, said operating member being accessible from outside the circuit breaker enclosing casing, and means movable during the assembly and calibration of the breaker for shifting the position of the operating member relative to the core to calibrate the electromagnetic trip means, and means for substantially preventing unauthorized change in the setting of said movable calibrating means.

13. In a circuit breaker, an enclosing casing, relatively movable contacts in said casing, a trip device in said casing operable in response to predetermined conditions to cause opening of said contacts including a magnetically actuated trip element movable from a normal position to a tripping position to eifect operation of the trip device and a thermally responsive bimetal element heated in response to the current of the circuit and operable when heated a predetermined amount to effect operation of the trip device, said bimetal element being given a permanent setting during the assembly and calibration of the device, adjusting means for adjusting the trip characteristic of said magnetically actuated trip element comprising an operating member normally engaged by said trip element and mounted for limited adjusting movement to adjust the normal position of said trip element and means movable to shift the position of said movable operating member to calibrate the device for the maximum current setting, said operating member being accessible from outside said casing, and means for preventing unauthorized change in the setting of said movable means.

14. A circuit breaker trip device comprising an electromagnet energized by the current of the circuit, said electromagnet having a pivoted armature movable to an attracted position in response to said predetermined current conditions to cause automatic opening of the breaker; and a pivoted lever having an end engaging the back of said armature and movable along the back of said armature toward and away from the pivot of said armature to adjust the normal position of said armature.

HILLER D. DORFMAN. 

